package com.starimmortal.druid.configuration;

import com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceAutoConfigure;
import com.alibaba.druid.spring.boot.autoconfigure.properties.DruidStatProperties;
import com.alibaba.druid.util.Utils;
import org.springframework.boot.autoconfigure.AutoConfigureAfter;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.servlet.*;
import java.io.IOException;

/**
 * Druid 连接池配置类
 *
 * @author william@StarImmortal
 * @date 2022/09/29
 */
@Configuration
@AutoConfigureAfter(DruidDataSourceAutoConfigure.class)
public class DruidConfiguration {

	/**
	 * 带有广告的common.js全路径，druid-1.2.11
	 */
	private static final String FILE_PATH = "support/http/resources/js/common.js";

	/**
	 * 原始脚本，触发构建广告的语句
	 */
	private static final String ORIGIN_JS = "this.buildFooter();";

	/**
	 * 替换后的脚本
	 */
	private static final String NEW_JS = "//this.buildFooter();";

	/**
	 * 去除Druid监控页面的广告
	 * @param properties DruidStatProperties属性集合
	 * @return {@link FilterRegistrationBean}
	 */
	@Bean
	@ConditionalOnWebApplication
	@ConditionalOnProperty(name = "spring.datasource.druid.stat-view-servlet.enabled", havingValue = "true")
	public FilterRegistrationBean<RemoveAdFilter> removeDruidAdFilter(DruidStatProperties properties)
			throws IOException {
		// 获取web监控页面的参数
		DruidStatProperties.StatViewServlet config = properties.getStatViewServlet();
		// 提取common.js的配置路径
		String pattern = config.getUrlPattern() != null ? config.getUrlPattern() : "/druid/*";
		String commonJsPattern = pattern.replaceAll("\\*", "js/common.js");
		// 获取common.js
		String text = Utils.readFromResource(FILE_PATH);
		// 屏蔽 this.buildFooter(); 不构建广告
		final String newJs = text.replace(ORIGIN_JS, NEW_JS);
		FilterRegistrationBean<RemoveAdFilter> registration = new FilterRegistrationBean<>();
		registration.setFilter(new RemoveAdFilter(newJs));
		registration.addUrlPatterns(commonJsPattern);
		return registration;
	}

	/**
	 * 删除druid的广告过滤器
	 *
	 * @author BBF
	 */
	private static class RemoveAdFilter implements Filter {

		private final String newJs;

		public RemoveAdFilter(String newJs) {
			this.newJs = newJs;
		}

		@Override
		public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
				throws IOException, ServletException {
			chain.doFilter(request, response);
			// 重置缓冲区，响应头不会被重置
			response.resetBuffer();
			response.getWriter().write(newJs);
		}

	}

}
